Four deep sea fish and invertebrate assemblages from the northern Spanish slope were identified and related to geographic and bathymetric factors. The Peñas Cape comprises a boundary area splitting the more productive, wider and sandy western shelf from the less productive, narrow and muddy eastern part. The four faunal assemblages described were a shelf-slope transition assemblage (SST, 400-500 m); two upper slope assemblages (500-650 m), one corresponding to the western area of Cape Peñas and one to the eastern area; and a middle slope assemblage (650-750 m). The SST was dominated by plankton-feeding fish and was hence less diverse than the other strata. This dominance was more evident west of the Peñas Cape, where upwelling was stronger. Regarding invertebrates, plankton-feeding fish and benthos-feeding invertebrates dominated the SST, whereas zooplankton-feeding and deposit-feeding invertebrates dominated the middle slope. The western assemblages were richer in species as a consequence of a more complex food web, especially of guilds related to water column production: plankton-feeding fish and filter- and zooplankton-feeding invertebrates.